This invention relates to drive mechanisms for equipment of the type having a ground engaging wheeled unit control by a handle element pivoted to the ground engaging element. The invention is particularly directed to a reversible drive for such equipment, wherein a single multiple function motor is provided on the ground engaging body, such as in a vacuum cleaner, the motor power of the motor also being coupled to drive the body unit along the floor.
While the invention is particularly adaptable for use with upright vacuum cleaners, and will thus be disclosed in the following specification, it is apparent that features thereof may also be adaptable to other equipment, such as but not limited to lawn mowers and the like, without departing from the scope of the invention.
Vacuum cleaners of one type, known as "upright" vacuum cleaners, are comprised of a body unit having floor engaging wheels, and an operating motor incorporated therein. The motor serves to drive a conventional vacuum unit, as well as to rotate a brush roll. This type of vacuum cleaner also is provided with a handle or grip, connected generally pivotably to the body element by way of a rod or shaft, such that an operator may push the body element along a floor.
In the past, the operator has generally provided all of the force necessary for moving the body element along the floor. Since the body element may be relatively heavy due to the incorporation of the motor therein, the use of such vacuum cleaners, particularly those of high capacity, can be fatiguing.
As a result, various forms of motor driven equipment of the above type has been developed. In one general category of the equipment, mechanical coupling means are provided for coupling the motor to the wheels, the coupling means of course requiring the provision of some form of clutch. The clutch controls employed for this purpose have not, to the applicant's knowledge, been entirely satisfactory, since the space permissible for the introduction of the feature of reversible control is limited, and the cost of the motor drive feature must be held to a low value, while still enabling simple and fault free control of the device. In other words, it is difficult to introduce reversible motor drive into such equipment as upright vacuum cleaners, while enabling comfortable control over the motor drive feature in both the forward and reverse directions, such that the operator has no difficulty in controlling the device.
The most natural form of control involves the use of a handle control arranged so that low pressure forces on the handle in the direction of desired movement can effect the operation of the clutch, so that the motive power for the body unit is derived mainly from the motor. By this technique, the drive of the body unit should appear to be "normal", i.e., the operator should have the feeling that the motor is only assisting in the movement of the body or floor unit, whereby a smooth control of the device is attainable. Further, the motor power to the wheels of the body unit should not be influenced by other factors such as, for example, the angle between the floor surface and the pivotable rod or shaft, so that the control unit is not dependent upon the physical stature of the operator.
In a second type of control, the handle may be provided with an electric control device for controlling the wheel drive clutch or clutches. Insofar as the applicants are aware, however, drive systems of this type, especially for vacuum cleaners, have in the past not been commercially acceptable.
The present invention is therefore directed to the provision of a motor driven device of the above type, especially a vacuum cleaner, wherein the above disclosed problems are overcome, and wherein the control of the device is effected by mechanical means.
Briefly stated, in accordance with the invention, an upright vacuum cleaner is provided having a single motor for driving the vacuum pump and the brush rolls, and also for continuously driving a bevel pinion gear by way of Evoloid gears, such that the bevel pinion is continuously driven at a substantially constant rate that is low with respect to the speed of the motor. The bevel pinion continuously drives a pair of bevel gears in relatively opposite directions of rotation, and a Bowden cable is provided coupled to selectively effect the engagement of clutches with the bevel gears, to enable the mechanical coupling to the wheels of the body unit.
The Bowden cable is preferably strung through the control rod or shaft of the device, and is connected to the handle or grip at the upper end thereof, so that relative sliding movement of the handle on the shaft can effect the control of the clutch.
In various other features of the invention, for example, levers interposed between the clutch and the Bowden cable may have notches or projections therein which are adapted to engage a portion of the rod or shaft in an upright position thereof, so that motive power cannot be applied to the wheels in a rest position of the equipment.
Further, a latch, lock or the like may be provided on the handle or grip, to restrain the relative slidable movement thereof, and thereby to enable the operator to provide the sole motive power for the drive wheels.